Potential Sources of Salts from Water-Rock Interaction during Hydraulic Fracturing: An Experimental Study
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Date
2015-12
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The Ohio State University
Abstract
Studying the composition and chemistry of post-hydraulic fracturing flowback waters is important for understanding water-rock interaction in the subsurface and for how fluids injected into a well during the fracturing process can affect flowback water chemistry. A recent issue has risen involving the elevated concentrations of salts as total dissolved solids present in flowback waters. Scientists have been investigating whether these salts are being dissolved from the formation itself or if hydraulic fracturing fluids affect salt concentrations. This question was investigated by performing sequential leach experiments to determine how cation and anion concentrations dissolved into solution over time. Core and cuttings samples were obtained from southeastern Ohio. Core samples are from the Point Pleasant Formation and cuttings samples are from the Utica Formation. Various techniques were used to analyze samples including X-Ray diffraction (XRD) for bulk mineralogy, scanning electron microscopy (SEM) for mineral-textural and elemental data, and the use of PHREEQC Geochemical Modeling to determine saturation indices. The use of the SEM allowed for the assessment of the amount of barite and other minerals present after sequential leaching.
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Keywords
hydraulic fracturing, flowback waters, Point Pleasant Formation, Utica Formation, sequential leach experiments